How to Operate Pumps in Parallel
Parallel pumping is a process that uses two or more pumps connected in parallel to control the fluid flow or use an additional pump(s) as an emergency backup. This type of pump configuration is common in wastewater plants and domestic water supply systems, where the flow rate gets distributed across the pumps connected in parallel while the pressure head remains constant.
What is Parallel Operation?
Parallel operation is the process by which two or more pumps work in parallel as a system to pump the same fluid. The system takes the fluid from a common suction point and discharges the pressurized fluid into a common header. Therefore, the discharge head always remains constant in parallel pumping systems.
Moreover, the amount of fluid in each pump is equally divided. For example, in parallel pumping systems with three pumps, each pump will handle 33% of the load capacity. However, in many cases, the additional pumps arranged parallel with the main pump sit idle while the main pump handles 100% of the load. The auxiliary pumps, in this case, are only used for emergency backup.
Benefits of Operating Pumps in Parallel
There are multiple advantages to having pumps working in a parallel system.
- Parallel pumps help control flow rates while keeping the head constant.
- This system allows using pumps with different hydraulic characteristics together, provided they have the same head characteristics.
- A parallel pump system has a higher degree of standby capacity compared to a single pump.
- Parallel pumping helps save both energy and money.
Drawbacks of Operating Pumps in Parallel
- While parallel pump systems are much more cost-effective than a single pump system, many design-level challenges must be considered to obtain desired performance from the system.
- One of the major concerns with operating pumps in parallel is compatibility. The performance curves of the pumps being operated in parallel should be very close, or the system will fail.
- Even if you bring two identical pumps of the same make and model, it is essential to compare and align the performance charts of each pump to ensure reliability and overall system energy efficiency.
- While it's possible to have two dissimilar pumps work in parallel, the head should be matched at the rate points in the range of 3 - 4 points.
Parallel Pumping Applications
Pumps are often used in industries where there is a need to control flow rates with a constant head, chilled water distribution systems being a common example. Industrial hydronic systems can also take advantage of parallel pump systems to increase reliability and reduce operating costs.
Get Help from The Experts At Hayes Pump
Configuring pumps in parallel is more than just connecting pumps together. As discussed, there are several variables you need to consider before an effective system is designed to offer the desired performance and cost savings.